Changes of adsorption capacity and pore distribution of biological activated carbon on advanced water treatment

Several problems such as unpleasant odor, taste and toxic halogenated organic compounds which are produced by the reaction of organic substances with chlorine that is used for disinfection have occurred in water purification plant for drinking water. Advanced water treatment with biological activated carbon (BAC) has been focused on, but there are few papers about pore volume decrease of activated carbon in BAC. In this study, the changes in cumulative TOC removal and pore volume distribution for two types of activated carbon from a bench-scale apparatus and a mini-column apparatus, to which river water was supplied after coagulation-sedimentation for a period of over 1200 days, were investigated. Adsorption abilities decreased considerably after ca 1000 days and the activated carbons became like sand. The cumulative TOC removals by the adsorption effect were asymptotic to constant values for each empty bed contact time. Though the removal efficiencies for both the activated carbons were approximately equivalent, the pore volume decreases were not uniform. The volume of smaller pores under 2 nm in diameter mainly decreased. Accumulations of minerals such as aluminium and calcium were small, and the pore volume decreases were mainly caused by the accumulation of organic substances. Almost all of the organic substances that accumulated in the activated carbon could be extracted by sodium hydroxide solution. The mean density of the organic substances that accumulated in the activated carbon was estimated to be 0.91 g/ml. Since the pore volume decrease of the activated carbon was small compared with the removal amounts by the adsorption effect, a large amount of organic substances that had adsorbed once disappeared and the pore volume of the activated carbon was regenerated.

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Characteristics of Nanoparticles in Drinking Water Treatment using Biological Activated Carbon

MATEC Web of Conferences ◽

10.1051/matecconf/201815603039 ◽

2018 ◽

Vol 156 ◽

pp. 03039

Author(s):

Reni Desmiarti ◽

Yoji Morishita ◽

Tomonari Fujisawa ◽

Yasushi Ishiguro ◽

Toshiro Yamada ◽

...

Keyword(s):

Drinking Water ◽

Activated Carbon ◽

Water Treatment ◽

Size Distribution ◽

Drinking Water Treatment ◽

Granular Activated Carbon ◽

Volume Distribution ◽

Biological Activated Carbon ◽

Distribution Ranges ◽

Flow Experiments

Characteristics of nanoparticles in drinking water treatment were performed using five types of biological activated carbon (BAC) columns (BAC1-BAC5) in continuous flow experiments. The BAC was created by covering granular activated carbon (GAC) with attached microorganisms from water samples taken from the Nagara River in Japan. The total running time was about 2000 h. The characteristics of the nanoparticles were investigated based on size distribution and volume distribution measured by Zetasizer Nano. Total dissolved organic carbon (DOC) and ultraviolet absorbance at 260 nm (UV260) were also studied. The important results in this study were that the detached nanoparticles in the effluent were within the size distribution ranges of 0.26~5.62 nm, 0.62~3.62 nm, 0.62~3.12 nm, 0.62~4.19 nm, and 0.62~6.50 for BAC 1, 2, 3, 4 and 5, respectively. The profile of peak size and peak number along the bed depth of the BAC columns was evaluated for better understanding the characteristics of the nanoparticles. This result is very important for improving drinking water treatment using granular activated carbon to remove microorganisms.

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Charge vs. Porosity - Some Influences on the Adsorption of Natural Organic Matter (NOM) by Activated Carbon

Water Science & Technology ◽

10.2166/wst.1999.0474 ◽

1999 ◽

Vol 40 (9) ◽

pp. 191-198 ◽

Cited By ~ 18

Author(s):

G. Newcombe

Keyword(s):

Activated Carbon ◽

Pore Volume ◽

Activated Carbons ◽

Surface Concentration ◽

Volume Distribution ◽

Electrostatic Effects ◽

Adsorption Mechanisms ◽

Enhanced Adsorption ◽

Aromatic Ring Interactions ◽

Filling Mechanism

The adsorption of NOM ultrafiltration fractions onto ten activated carbons was studied. The aim of the research was the clarification of the effects of carbon charge and pore volume distribution and NOM charge and molecular weight on adsorption. The effect of pH and ionic strength on adsorption mechanisms was determined, and it was found that, in the absence of strong electrostatic effects, adsorption occurred by a pore filling mechanism in which the available pore volume was filled. At neutral pH the NOM has a significant negative charge which can affect the adsorption in several ways. At low surface concentrations on activated carbon with positive surface groups there is direct surface-NOM electrostatic attraction (screening reduced adsorption). At higher surface concentrations the adsorption becomes predominantly a physical surface-NOM attraction, possibly due to hydrophobic or aromatic ring interactions. The electrostatic effects are mainly caused by the lateral repulsion of the NOM that prevents the close-packed arrangement apparent at pH 3 (screening enhanced adsorption). For one activated carbon it was shown that the degree of ionisation of the adsorbed NOM is strongly dependent on the surface concentration.

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Pesticide removals in the nitrifying expanded-bed filter at drinking water treatment plant

Journal of Science and Technology in Civil Engineering (STCE) - NUCE ◽

10.31814/stce.nuce2021-15(1)-01 ◽

2020 ◽

Vol 15 (1) ◽

pp. 1-13

Author(s):

Nguyet Thi-Minh Dao ◽

The-Anh Nguyen ◽

Viet-Anh Nguyen ◽

Mitsuharu Terashima ◽

Hidenari Yasui

Keyword(s):

Drinking Water ◽

Activated Carbon ◽

Water Treatment ◽

Treatment Plant ◽

Drinking Water Treatment ◽

Cost Effective ◽

Water Treatment Plant ◽

Field Analysis ◽

Expanded Bed ◽

Biological Activated Carbon

The occurrence of pesticides even at low concentrations in drinking water sources might induce potential risks to public health. This study aimed to investigate the removal mechanisms of eight pesticides by the nitrifying expanded-bed filter using biological activated carbon media at the pretreatment of a drinking water plant. The field analysis demonstrated that four pesticides Flutolanil, Buprofezin, Chlorpyrifos, and Fenobucard, were removed at 82%, 55%, 54%, and 52% respectively, while others were not significantly removed. Under controlled laboratory conditions with continuous and batch experiments, the adsorption onto the biological activated carbon media was demonstrated to be the main removal pathway of the pesticides. The contribution of microorganisms to the pesticide removals was rather limited. The pesticide removals observed in the field reactor was speculated to be the adsorption on the suspended solids presented in the influent water. The obtained results highlighted the need to apply a more efficient and cost-effective technology to remove the pesticide in the drinking water treatment process. Keywords: biological activated carbon; drinking water treatment; nitrifying expanded-bed filter; pesticide removal.

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Biodegradation of Organic Substances by Biological Activated Carbon – Simulation of Bacterial Activity on Granular Activated Carbon

Water Science & Technology ◽

10.2166/wst.1992.0654 ◽

1992 ◽

Vol 26 (9-11) ◽

pp. 2031-2034 ◽

Cited By ~ 7

Author(s):

W. Nishijima ◽

M. Tojo ◽

M. Okada ◽

A. Murakami

Keyword(s):

Activated Carbon ◽

Community Structure ◽

Granular Activated Carbon ◽

Bacterial Activity ◽

Organic Substances ◽

Aminobenzoic Acid ◽

Biological Activated Carbon ◽

Support Medium ◽

Attached Bacteria ◽

The Difference

Biodegradation of organic substances by attached bacteria on biological activated carbon (BAC) was studied to clarify the advantages of granular activated carbon (GAC) as support media over conventional media without adsorption capacity with regard to biodegradation activity and community structure of attached bacteria. Anthracite (AN) was used as reference support medium without adsorbability. Low molecular organic substances with different biodegradability and adsorbability (phenol, glucose, benzoic acid and m-aminobenzoic acid) were fed into completely mixed BAC and AN reactors. The rate of biodegradation by BAC reactors fed with biodegradable organic substances was approximately 3 times as high as that by AN reactors. The difference in adsorbability of organic substances onto GAC had little effects on the rate of biodegradation. The structure of GAC with micro and macro pores did not provide better habitat for attached bacteria with regard to the size of population in comparison with anthracite without pores. The rates of biodegradation per attached bacteria for biodegradable organic substances in the BAC reactors were from 1.7 to 4.9 times higher than those in the AN reactors. GAC, as a bacterial support media, stimulated the biodegradation activity of each bacteria without increase in their population and probably with little change in their species composition. Although the number of attached bacteria on BAC was not different significantly from that on anthracite, m-aminobenzoic acid with low biodegradability was degraded only by the GAC reactor.

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Adsorption of MIB by activated carbons produced using several activation techniques

Water Science & Technology Water Supply ◽

10.2166/ws.2002.0178 ◽

2002 ◽

Vol 2 (5-6) ◽

pp. 265-270

Author(s):

R. McCallum ◽

F. Roddick ◽

M. Hobday

Keyword(s):

Heat Treatment ◽

Activated Carbon ◽

Water Treatment ◽

Organic Compounds ◽

Activated Carbons ◽

Alkali Treatment ◽

Power Station ◽

Steam Activation ◽

Pre Treatment ◽

Physical And Chemical

Water treatment authorities use activated carbon as the best available technology to remove low molecular weight organic compounds from potable water. In Australia, pollutants of concern include secondary metabolites from bacterial and cyanobacterial blooms which are highly odorous and, in some cases, toxic. Of these compounds, 2-methylisoborneol (MIB) is one of the most common and its unpleasant musty earthy odour can be detected at or above approximately 10 ng/L. Difficulties in using activated carbon to target such small organic compounds arise when the water has high concentrations of natural organic matter (NOM), as these compounds also adsorb on activated carbon. The adsorption of NOM on activated carbon increases the cost of using this material in water treatment due to competition with the target organic compounds, reducing the capacity of the activated carbon for the latter. The surface of activated carbon can be tailored during production to provide physical and chemical characteristics that can either aid or hinder the adsorption of particular compounds. One source of activated carbon currently under investigation at RMIT University is brown coal char waste from power stations. This waste, currently disposed of to landfill, is potentially an option for activated carbon production. This material has the advantage that it has already been carbonised at around 500°C in the power generation process. This means that less energy is required to produce activated carbon from power station char compared to coal, making the final product cheaper to produce. Previous work at RMIT has shown that steam activated power station char can remove organic compounds from water. Production of a range of activated carbons from power station char (PSC) was undertaken using different activation methods, including steam activation, steam activation with acid pre-treatment, alkali heat treatment, and Lewis acid heat treatment. The different activation methods produced activated carbons with different pore size distributions, in particular, the acid pre-treatment increased the surface area and porosity significantly compared with steam activation, and the alkali treatment increased the microporosity. Adsorption of MIB on these activated carbons was evaluated to determine the relationship between physical and chemical interactions of the activated carbon and adsorption. Adsorption of MIB on these activated carbons was found to be dependent on the secondary micropore volume. Lewis acid treatment and alkali treatment was not involved in the generation of many of these secondary pores, hence carbons from these treatments did not perform well in adsorption tests. The best adsorption results were achieved with steam activated or acid treated steam activated samples which performed comparably to commercial products. Initial results showed that competition from NOM adsorption was lowest with the PSC activated carbons, allowing greater adsorption of MIB, compared with the commercial activated carbons.

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Phenol adsorption on high microporous activated carbons prepared from oily sludge: equilibrium, kinetic and thermodynamic studies

Scientific Reports ◽

10.1038/s41598-019-55794-4 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 11

Author(s):

N. Mojoudi ◽

N. Mirghaffari ◽

M. Soleimani ◽

H. Shariatmadari ◽

C. Belver ◽

...

Keyword(s):

Activated Carbon ◽

Pore Volume ◽

Activated Carbons ◽

Ph Value ◽

Chemical Activation ◽

Bet Surface Area ◽

Polluted Water ◽

Oily Sludge ◽

Maximum Adsorption Capacity ◽

Adsorption Desorption

AbstractThe purpose of this study was the preparation, characterization and application of high-performance activated carbons (ACs) derived from oily sludge through chemical activation by KOH. The produced ACs were characterized using iodine number, N2 adsorption-desorption, Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The activated carbon prepared under optimum conditions showed a predominantly microporous structure with a BET surface area of 2263 m2 g−1, a total pore volume of 1.37 cm3 g−1 and a micro pore volume of 1.004 cm3 g−1. The kinetics and equilibrium adsorption data of phenol fitted well to the pseudo second order model (R2 = 0.99) and Freundlich isotherm (R2 = 0.99), respectively. The maximum adsorption capacity based on the Langmuir model (434 mg g−1) with a relatively fast adsorption rate (equilibrium time of 30 min) was achieved under an optimum pH value of 6.0. Thermodynamic parameters were negative and showed that adsorption of phenol onto the activated carbon was feasible, spontaneous and exothermic. Desorption of phenol from the adsorbent using 0.1 M NaOH was about 87.8% in the first adsorption/desorption cycle and did not decrease significantly after three cycles. Overall, the synthesized activated carbon from oily sludge could be a promising adsorbent for the removal of phenol from polluted water.

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Particle separation as a pretreatment of an advanced drinking water treatment process by ozonation and biological activated carbon

Water Science & Technology ◽

10.1016/s0273-1223(98)00301-1 ◽

1998 ◽

Vol 37 (10) ◽

Cited By ~ 7

Keyword(s):

Drinking Water ◽

Activated Carbon ◽

Water Treatment ◽

Treatment Process ◽

Particle Separation ◽

Drinking Water Treatment ◽

Biological Activated Carbon ◽

Water Treatment Process ◽

Advanced Drinking Water Treatment

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Effect of Activating Agent on the Preparation of Bamboo-Based High Surface Area Activated Carbon by Microwave Heating

High Temperature Materials and Processes ◽

10.1515/htmp-2014-0228 ◽

2016 ◽

Vol 35 (6) ◽

pp. 535-541 ◽

Cited By ~ 1

Author(s):

Hongying Xia ◽

Jian Wu ◽

Chandrasekar Srinivasakannan ◽

Jinhui Peng ◽

Libo Zhang

Keyword(s):

Activated Carbon ◽

Microwave Heating ◽

Surface Area ◽

Pore Volume ◽

Activated Carbons ◽

High Surface ◽

High Surface Area ◽

Significant Proportion ◽

Mixture Ratio ◽

Activating Agent

AbstractThe present work attempts to convert bamboo into a high surface area activated carbon via microwave heating. Different chemical activating agents such as KOH, NaOH, K2CO3 and Na2CO3 were utilized to identify a most suitable activating agent. Among the activating agents tested KOH was found to generate carbon with the highest porosity and surface area. The effect of KOH/C ratio on the porous nature of the activated carbon has been assessed. An optimal KOH/C ratio of 4 was identified, beyond which the surface area as well as the pore volume were found to decrease. At the optimized KOH/C ratio the surface area and the pore volume were estimated to be 3,441 m2/g and 2.093 ml/g, respectively, with the significant proportion of which being microporous (62.3%). Activated carbon prepared under the optimum conditions was further characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). Activated carbons with so high surface area and pore volume are very rarely reported, which could be owed to the nature of the precursor and the optimal conditions of mixture ratio adopted in the present work.

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